The present invention generally relates to clamping devices and, more particularly, to such devices which are specifically designed for use in the movie industry as supports for lighting and rigging equipment.
One particular clamping mount of the type disclosed herein is the subject of U.S. Pat. No. 5,276,949, issued Jan. 11, 1994 to Steven L. Cordellini. The Cordellini clamp has become more or less standard in the motion picture lighting industry. Broadly considered, it comprises a pair of jaws and a partially threaded shaft. One of the jaws is fixed in position midway along the shaft adjacent the threaded portion. The other jaw is slidable along the threaded portion and is driven toward the fixed jaw to clamp the device on a support of some sort by a knob which has internal threads that made with the threaded portion of the shaft.
To mount a light or piece of rigging hardware on the clamp device, it is affixed to the end of the shaft remote from the threaded portion. This end is shaped with a standard configuration for insertion into mounting receptacles that are standard on whatever items of equipment are to be mounted on the clamp device. Thus, when the knob is turned to tighten the two jaws of the device to grip a support member, the piece of lighting or rigging equipment which is attached to the unthreaded end of the shaft is supported as desired.
While closing the jaws by rotating the knob serves to clamp the device in position, rotating the knob in the opposition direction does not always result in the device unclamping itself. Due to slight distortion of the slidable jaw resulting from the force used to clamp the jaws on a support element, the slidable jaw often remains locked in position when the knob is loosened. This is a common occurrence and it generally requires a tap from a hammer or the like to release the slidable jaw to an unclamped position.
A number of items in the catalog of Matthews Studio Equipment, Inc. are listed and described in the introduction of the Cordellini patent. The reader is referred to the Matthews catalog and to the Cordellini patent for a description of the various items A through R from the catalog. Cordellini points out numerous deficiencies of the various items A through R and asserts the benefits of the Cordellini clamp over all of the prior art devices. The clamping device of the present invention is a significant advance in the art over the Cordellini clamp and it is expected to supersede the Cordellini clamp because of its numerous benefits, improvements and advantages with respect thereto.
In brief, arrangements in accordance with the present invention comprise a pair of particularly configured jaws mounted on a threaded shaft with an internally threaded knob for adjusting the spacing between the jaws, both in closing the jaws to establish the clamping function about some support member, such as a pole, and in driving them apart to actively release the clamp. In addition, the invention can be used as a xe2x80x9cwall spreaderxe2x80x9d by propelling the jaws apart in order to establish a mounting on a pair of opposed parallel surfaces, such as the sides of a door frame.
The threaded shaft is threaded throughout its length with a No. 8 ACME thread. Thus, for economy of fabrication, it can simply be cut from longer threaded rod stock and does not require the special threading operation which is necessary in fabricating the device disclosed in Cordellini. The free end of the shaft has an internally threaded bore for receiving a threaded mounting pin to establish the configuration shown in the patent where the end of the shaft is formed in the configuration of a mounting pin. In addition, each of the jaws is provided with a plurality of threaded holes to receive a threaded mounting pin at different points on the jaws and at different angles.
For ease of fabrication, the two jaws are formed in identical fashion to provide a variety of different surfaces which are particularly adapted to clamp onto support members of different shapes and sizes, for example, round poles or pipes, square or rectangular supports, large or small circular members and the like. The jaws are formed with clamping surfaces of different types, capable of clamping onto a wide variety of surfaces, at opposite ends of the jaws. Moreover, each of the jaws has its opposite faces shaped in complementary fashion to provide a V-shaped clamp groove in each face for permitting the jaws to clamp in either direction. The limits of the mounting surfaces (V-grooves and the like) on opposite faces of a given jaw device terminate at a plane for that face of the jaw, thereby serving to stabilize the clamp when it is mounted on any support member. In addition, each end of the jaw is provided with an opening of a size and shape to accommodate a carabiner for attaching a line, such as a cable, cord, rope or the like. If no carabiner is available, these opening accommodate the rope itself which may be passed through the opening and secured.
The fixed jaw is provided with a circular recess extending about the threaded shaft. This is to accommodate a projecting titanium sleeve which is installed in the adjustable jaw, thus permitting the two jaws to be closed together if desired without interference by the protruding sleeve. This titanium sleeve protects the material of the aluminum jaw from wear or binding against the threads of the shaft.
The adjustable jaw is provided with a U-shaped slot extending inwardly from one side of the jaw adjacent the titanium sleeve to receive a partially threaded brass sleeve during assembly of the adjustable jaw on the shaft. A xc2xe inch deep knob with an ergonomically designed three-bladed handle and a hexagonal one-inch nut, directly below the handle, all constituting one piece, is fixedly mounted at one end of the brass sleeve. The hexagonal nut is provided with six flats to accommodate a wrench which may be used to apply more torque than could be developed by manually turning the knob. At the end of the brass sleeve remote from the knob is a head portion extending radially outward from and surrounding the sleeve. A washer is affixed to the face of the head portion which is nearer the hexagonal nut and is immovable by design.
In assembling the adjustable jaw and the brass sleeve and knob on the threaded shaft, the head portion is slid laterally into the U-shaped slot of the jaw, together with another washer on the side opposite the first-mentioned washer, and the assembly is then threaded onto the threaded shaft.
The pins which are provided with the clamps of the present invention are of ⅝ inch diameter, which is standard in the industry. However, each pin is provided with two flats at its distal end for engagement by a wrench. The pins are of two different lengths, each having a threaded end xe2x85x9c inch in diameter. The threaded end is out from xe2x85x9c inch rod, No. 16 thread, which is mounted in a threaded bore in the end of the pin and held with a stainless steel roll pin.
A non-skid material is applied on all jaw faces. This can be developed by using a boat deck coating which is available from marine supply stores. This material serves to keep the metal, of the jaws from scratching items to which the clamp may be attached.
Other features and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.